Improvement in the manufacture of slabs for pavements



n. E. STEPHENS.

Improvement in the MnufacfurefSlabs for Pavement-s. No.128,670. Palentedmyzwn naa UNITED STATES PATENT OFFICE.

ROBERT EBRETT STEPHENS, OF OWEN SOUND, CANADA.

Specification forming `part of Letters Patent No. 128,670, dated July 2, 1872.

i SPECIFICATION. To all whom it may concern: l'

Be it known that I, ROBERT EnRE'r'r STE PHENs, of the town of Owen Sound, in the county of Grey, in the Province of Ontario, gentleman, haveinvented. a new and useful i Improved Art of Manufacturing Pressure- Formed Slabs for Pavements, Floors, Roofing, &c., and Slabs thereby produced;77 and I do hereby declare that the following is a full, clear, and exact description of my invention.

I take pitch or tar, or a mixture of both, and having placed it in a suitable vessel made of metal, and otherwise constructed in the ordinary manner to answer the purposes of a caldron and mixing-trough, the pitch or tar havin g become sufficiently heated to render it perfeet-ly iuid, I then add to it an equal quantity, by weight, of sawdust, and, by mixing thoroughly, incorporate the whole mass, heat being still applied of sufficient amount to keep the resinous substance fluid.

Although I have stated that an equal quantity of resinous substance is to be used with the sawdust, yet I do not confine myself to this exact proportion, as it will be varied in accordance with the quality of the sawdust and the thickness of non-combustible face required, as will be hereinafter described.

That my invention and the means of carrying it into eect may be the more easily understood, I have hereunto annexed drawing; but I do not claim any ofthe apparatus as part of my invention; neither do I confine myself to the use 0f the exact apparatus shown in the drawing, as both presses and boxes with movable sides (which form the principal part of it) have been used and can be used in so many forms to accomplishthe same result.'

Figure lrepresents an elevation ofthe truck.

Fig. 2 represents a plan of the truck. Fig. 3

represents details of bars.

In the drawing similar letters of reference indicate like parts.

Letter a is a truck of ordinary construction, either countersunk on the top or having a small ledge xed on so as to form a rectangular inclosure for the reception of the bars b and c, which are, by preference, generally one inch and one-fourth inch thick, respectively. The

ends d of these bars are, as shown in Figs. 1, 3, and 4, halved, every alternate bar being provided with a pin, e, which fits into a hole, in the halved end of the bar above it. g are lugs formed or cast on the inch bars for the purpose of keeping the other bars from shifting laterally. h is an iron plate, by preference about one-eighth inch thick, in size and shape such as to iitaccurately in the space formed by the bars. The modas operandi of my invention is as follows: The pitch or tar, having been heated, is mixed and thoroughly incorporated with the sawdust, and the truck a brought, preferably on a tramway, in close juxtaposition with the mixing-trough. In the rectangular inclosure formed by the ledge or countersinking described, and in contact with it on each side, are placed one row of the bars c, (or those onefourth inch thick,) the pins e fitting into the holes f serving to keep them in their proper relative positions. Into the space inclosed by these bars sand is poured until it reaches the level of the top of the bars c, which serve as a guide for a straight-edge passed over them t0 level the sand and sweep away any superfluous particles. The inch bars b, interlocked by means of the pins and holes e and f, are then put on, the lugs g preventing them from shifting in any way from their position exactly over the bars c. Into the space inclosed by these bars b is poured the mixture of resinous substance and sawdust, a straight-edge being used, as before, to level it even with the top of the bars. Upon the mixture, and covering the whole surface of it, but clear of the surrounding bars, is placed a thin iron plate, h, preferably about one-eighth inch thickand greased to prevent any chance of the mixture.

adhering to it. A sheet of paper placed under it may serve the same purpose. Upon the top of the inch bars b is built up another tier of the one-fourth inch bars c; .the sand being spread and leveled as before, the bars b are built up, the'mixture place therein and leveled, and plate h put on as before. This process is repeated as often as may be convenient, the bars b and c being built up in alternate stages, and the alternate layers of sand and the mixture of pitch or tar and sawdust arranged with the separating plates of iron. The whole is crowned with a plate of iron of the same size and shape, but somewhat heavier than the plates h. The truck with its burden is then removed from the mixing-trough to the press, when, by any suitable device-such as by lowering a section of the rails-the bottom ofthe truck is brought to rest evenly on the floor of the press. Pressure is then applied in any ordinary manner until a portion of the pitch, tar, or other resinous substance held by the sawdust has been forced from it and driven to mix with the sand, thus forming a slab, so to say, sand-faced, the particles of sand being held together and to the backing of sawdust by the pitch or tar with which they are incorporated. The iron bars are then taken down, the plates removed, the loose sand brushed away, and the slabs piled or otherwise stored till required. The truck bearing the bars and plates is then run back to the mixing-trough and the same process gone through again. By using` a different track the process may be continuous, one car being loaded while the other is at the press.

It willbe seen thatby myinvention stratified slabs are formed, faced with sand, and valuable not only for the non-combustible nature of their facing, but also for the hard rough sur face, well calculated to resist wear, which they present.

The slabs are calculated to be three feet by one foot six inches, with a thickness of about one-half foot; but I do not conine my self to these dimensions, as the size and thickness may often be advantageously variedto suit particular circumstances.

Having thus described the construction and operation of my invention, I beg to state that What I claim as my invention, and Wish secured by Letters Patent, is as follows:

l. The art of manufacturing stratified slabs by pressure, substantially as described.

2. The stratified slabs, constructed as described.

Owen Sound, the 12th day of December, A. Y

R. E. STEPHENS.

Clerk of the Peace, County of Grey, Ontario. 

